An efficient, rapid and solvent-free synthesis of branched imines using sulfated anatase-titania as a novel solid acid catalyst

An eco-friendly solid acid catalyst sulfated anatase-titania (TiO2-SO42-) has been used for the synthesis of branched imine derivatives from 2,6-di(propan-2-yl)aniline with different substituted aromatic aldehydes by simple physical grinding. This sulfated titania gives an excellent yield with short reaction time and is an inexpensive, easily recyclable catalyst for this reaction. Twenty imines with different substituted aldehydes have been synthesized. However, yields are slightly affected by the substituents present in the aldehydes and their positions. Electron-withdrawing group favours a faster reaction than electron donating group. Aldehydes with para substitution give better yield than ortho and meta substituted aldehydes. To the best of our knowledge, this is the first report for the synthesis of branched imines in this catalytic way.